This section provides background information related to the present disclosure which is not necessarily prior art.
Power supplies having outputs coupled in series each commonly include an overcurrent protection (OCP) scheme. Some typical OCP schemes include a latching overcurrent protection scheme and a foldback current limiting scheme. For example, FIG. 1A illustrates a voltage-current (V-I) characteristics curve 100 of two series coupled power supplies each employing a latching OCP scheme in which an output current increases until it reaches an OCP threshold (e.g., 130% of a rated output current). At that time, the output current and voltage terminate to zero.
FIG. 1B illustrates a V-I characteristics curve 102 of two series coupled power supplies each employing a foldback current limiting scheme. In this case, one of the power supplies enters its foldback mode when an output current reaches its OCP threshold thereby causing the output current and an output voltage to decrease linearly. The output current then increases again until the other power supply enters its foldback mode causing the output current and the output voltage to decrease linearly again.
FIG. 1C illustrates a V-I characteristics curve 104 of two series coupled power supplies each employing a constant current limiting scheme and a foldback current limiting scheme in which an output current is held steady at a particular level until an output voltage reaches a defined threshold. At which time, the power supplies enter their foldback mode as explained above.